The installations for the production of large quantities of oxygen and/or nitrogen by air distillation often comprise a refrigeration tower which serves to refrigerate the water for cooling the compressed air, so as to lower the temperature of the air upon its entry into the adsorbent chambers. This tower is supplied with residual gas (impure nitrogen or air enriched in nitrogen) from the distillation apparatus.
In the usual technique, only a portion of the residual gas supplies the refrigeration tower, and the rest is used only for the regeneration of the adsorbent. Thus, the usual regeneration cycle alternates a heating phase and a cooing phase. The residual gas then leaves the chamber saturated in water, with a very variable temperature from about -5.degree. C. to +40.degree. C. This residual fraction can therefore not be used effectively to refrigerate the water.
This technique has the drawback of greatly limiting the flow rate of residual gas available to refrigerate the water, and hence of limiting the lowering of the temperature of this water. It is thus necessary to install in the conduit of water from the refrigeration tower a refrigeration group having a high refrigeration power.